ignore some codegen tests in debug mode

Author: RalfJung

src/test/codegen/issue-45222.rs

@@ -1,4 +1,5 @@
 // compile-flags: -O
+// ignore-debug: the debug assertions get in the way
 
 #![crate_type = "lib"]
 

src/test/codegen/issue-45466.rs

@@ -1,4 +1,5 @@
 // compile-flags: -O
+// ignore-debug: the debug assertions get in the way
 
 #![crate_type="rlib"]
 

src/test/codegen/swap-small-types.rs

@@ -1,5 +1,6 @@
 // compile-flags: -O
 // only-x86_64
+// ignore-debug: the debug assertions get in the way
 
 #![crate_type = "lib"]